Conventional intake manifold systems of internal combustion engines for passenger cars and commercial vehicles are generally designed for maximum efficiency at high or high medium engine speeds. Such manifolds typically have fixed cross-sectional areas with no provision for adjusting the velocity of the air-fuel mixture flow at low-medium or low speeds. With a fixed cross-section, the velocity of the air-fuel mixture decreases at low engine speeds or low revolutions-per-minutes (“RPMs”). As a result, these engines are noticeably inefficient in terms of power and fuel consumption when the engine is operating at low RPMs.
Certain prior art intake manifold systems have been designed to increase the air velocity by decreasing the cross-sectional of the intake runners at low RPMs. For example, recent developments in intake manifolds have implemented a flat valve plate positioned within the intake runner that is attached to one side of the intake runner by a single pivot. At low RPMs, the valve plate is actuated to rotate about the single pivot to decrease the cross-sectional area of the intake runner.
The object of such prior art designs is to increase the velocity of the air-fuel mixture during periods of low RPMs (i.e., low engine speeds) to ensure smoother and more efficient operation of the engine in terms of power and efficiency. However, such systems also have many drawbacks including the significant torque applied to the single pivot during engine operation, which compromises the structure and operation of the manifold system. Moreover, such systems have a design flaw in which the tip of the valve plate does not extend closer to the combustion chamber when the valve plate is in the extended (i.e., the smaller cross-section) position, reducing the effectiveness of increasing air fuel velocity in the combustion chamber. Such design requires a larger mounting flange at the head intake port surface to accommodate the mounting surface seal and have the valve plate tip near the combustion chamber. Accordingly, there is a need for improvement in the art.